In no particular order of course, although the obvious two top groundstrokes belong to Maria and Serena and I don't think anyone else can really compare off both wings simply because they're the two players who can actually consistently hit AMAZING fh and bhs no matter how much time they're given - ample time or completely rushed.

Stosur's, Ivanovic's and Kvitova's fh, when rushed, is definitely far from a weapon but they're huge and consistent enough to be at the top.

I actually quite like Sharapova and her game. She's great for the sport, and even her detractors have to admire her will to win. Her backhand is one of the most lethal shots in not just tennis but in sports. As much as I like Sharapova, though, I don't see how people can't see how her forehand is probably one of the shakiest on the tour.